dateframe取数据

import numpy as np
import pandas as pd
#
# x1=[1,2,3,4]
# x2=[4,5,6,7]
# x3=[7,8,9,10]
# df=pd.DataFrame(
#     {  'x1':x1,
#        'x2':x2,
#        'x3':x3
#        }
# )
# print(df)
# print(df['x1'])
# print(type(df['x1']))#<class 'pandas.core.series.Series'>#不含列名
# print(df['x1'].values)
# print(type(df['x1'].values))#<class 'numpy.ndarray'>
# print(df[['x1']])
# print(type(df[['x1']]))#<class 'pandas.core.frame.DataFrame'>含有列名
# #无索引，有列名
# #loc取某一个数,
# print(df.loc[1,'x2'])#5
# print(df.loc[0:1,['x1','x3']])#DataFrame
#
# #无索引，列名长
# print(df.iloc[1,1])
# print(df.iloc[0:2,1:3])
#
# #ix函数
# print(df.ix[1,1])
# print(df.ix[1,'x2'])

data = pd.DataFrame({'A':[1,2,3],'B':[4,5,6],'C':[7,8,9]},index=["a","b","c"])
print(data)
print(data.loc['a','B'])
print(data.loc['a':'c','A':'B'])